U.S. patent number 11,114,300 [Application Number 16/320,455] was granted by the patent office on 2021-09-07 for laser annealing apparatus, inspection method of substrate with crystallized film, and manufacturing method of semiconductor device.
This patent grant is currently assigned to THE JAPAN STEEL WORKS, LTD.. The grantee listed for this patent is THE JAPAN STEEL WORKS, LTD.. Invention is credited to Suk-Hwan Chung, Masashi Machida, Kenichi Ohmori, Ryosuke Sato.
United States Patent |
11,114,300 |
Ohmori , et al. |
September 7, 2021 |
Laser annealing apparatus, inspection method of substrate with
crystallized film, and manufacturing method of semiconductor
device
Abstract
A laser annealing apparatus (1) according to the embodiment
includes: a laser beam source (11) configured to emit a laser beam
(L1) to crystallize an amorphous silicon film (101a) on a substrate
(100) and to form a poly-silicon film (101b); a projection lens
(13) configured to condense the laser beam to irradiate a silicon
film (101); a probe beam source configured to emit a probe beam
(L2); a photodetector (25) configured to detect the probe beam (L3)
transmitted through the silicon film (101); a processing apparatus
(26) configured to calculate a standard deviation of detection
values of a detection signal output from the photodetector, and to
determine a crystalline state of the crystallized film based on the
standard deviation.
Inventors: |
Ohmori; Kenichi (Yokohama,
JP), Chung; Suk-Hwan (Yokohama, JP), Sato;
Ryosuke (Yokohama, JP), Machida; Masashi
(Yokohama, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
THE JAPAN STEEL WORKS, LTD. |
Tokyo |
N/A |
JP |
|
|
Assignee: |
THE JAPAN STEEL WORKS, LTD.
(Tokyo, JP)
|
Family
ID: |
1000005790484 |
Appl.
No.: |
16/320,455 |
Filed: |
July 14, 2017 |
PCT
Filed: |
July 14, 2017 |
PCT No.: |
PCT/JP2017/025652 |
371(c)(1),(2),(4) Date: |
January 24, 2019 |
PCT
Pub. No.: |
WO2018/037756 |
PCT
Pub. Date: |
March 01, 2018 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20190267240 A1 |
Aug 29, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 24, 2016 [JP] |
|
|
JP2016-163693 |
Jun 7, 2017 [JP] |
|
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JP2017-112516 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
29/78663 (20130101); H01L 21/268 (20130101); H01L
21/2011 (20130101); H01L 21/02675 (20130101) |
Current International
Class: |
H01L
21/20 (20060101); H01L 21/02 (20060101); H01L
29/786 (20060101); H01L 21/268 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
|
|
H03-097219 |
|
Apr 1991 |
|
JP |
|
H10-144621 |
|
May 1998 |
|
JP |
|
H11-121378 |
|
Apr 1999 |
|
JP |
|
2916452 |
|
Jul 1999 |
|
JP |
|
2001-332476 |
|
Nov 2001 |
|
JP |
|
2002-009012 |
|
Jan 2002 |
|
JP |
|
2008-028303 |
|
Feb 2008 |
|
JP |
|
2009-065146 |
|
Mar 2009 |
|
JP |
|
Other References
International Search Report from International Patent Application
No. PCT/JP2017/025652, dated Oct. 3, 2017. cited by
applicant.
|
Primary Examiner: Ahmed; Selim U
Attorney, Agent or Firm: SGPatents PLLC
Claims
The invention claimed is:
1. An inspection method of a substrate with a crystallized film,
the method comprising the steps of: (A) irradiating an amorphous
film over the substrate with a laser beam to crystallize the
amorphous film and to form the crystallized film; (B) irradiating
the crystallized film with a probe beam; (C) detecting, by a
photodetector, the probe beam transmitted through the crystallized
film; (D) changing an irradiation position of the probe beam onto
the crystallized film to acquire a plurality of detection values of
a detection signal from the photodetector; and (E) determining,
based on a standard deviation of the plurality of detection values,
a crystalline state of the crystallized film, wherein the laser
beam passes through a projection lens and forms a linear
irradiation region on the amorphous film by the projection lens,
and the photodetector detects the probe beam having passes through
the projection lens.
2. The inspection method according to claim 1, wherein the step (E)
comprises: comparing the standard deviation with a threshold; and
determining the substrate to be non-defective when the standard
deviation is less than the threshold or determining the substrate
to be defective when the standard deviation is equal to or greater
than the threshold.
3. The inspection method according to claim 1, wherein the step (E)
further comprises determining the crystalline state based on an
average value of the plurality of detection values.
4. The inspection method according to claim 1, wherein the probe
beam forms a linear illumination region on the crystallized film,
and the probe beam transmitted through the crystallized film is
condensed on the photodetector by a condenser lens.
5. The inspection method according to claim 1, wherein the step (D)
comprises conveying the substrate to change an irradiation position
of the laser beam and the irradiation position of the probe beam
while the substrate is being irradiated simultaneously with the
laser beam and the probe beam.
6. The inspection method according to claim 1, wherein the step (A)
comprises irradiating the amorphous film with the laser beam while
the substrate placed over a stage is being moved, the step (B)
comprises irradiating the amorphous film with the probe beam
outside the stage, and the step (D) comprises carrying the
substrate on the stage out by a robot hand to change the
irradiation position of the probe beam.
7. The inspection method according to claim 6, wherein the step (C)
comprises detecting, by the photodetector, the probe beam having
passed through the crystallized film twice or more.
8. A manufacturing method of a semiconductor device, the method
comprising the steps of: (a) forming an amorphous film over a
substrate; (b) irradiating the amorphous film with a laser beam to
crystallize the amorphous film and to form a crystallized film; (c)
irradiating the crystallized film with a probe beam; (d) detecting,
by a photodetector, the probe beam transmitted through the
crystallized film; (e) changing an irradiation position of the
probe beam onto the crystallized film to acquire a plurality of
detection values of a detection signal output from the
photodetector; (f) determining, based on a standard deviation of
the plurality of detection values, a crystalline state of the
crystallized film; and (g) re-irradiating the crystallized film
with the laser beam according to a determination result of the
crystalline state, wherein the laser beam passes through a
projection lens and forms a linear irradiation region on the
amorphous film by the projection lens, and the photodetector
detects the probe beam having passes through the projection
lens.
9. The manufacturing method according to claim 8, wherein the step
(f) comprises: comparing the standard deviation with a threshold;
and determining the substrate to be non-defective when the standard
deviation is less than the threshold or determining the substrate
to be defective when the standard deviation is equal to or greater
than the threshold.
Description
TECHNICAL FIELD
The present disclosure relates to a laser annealing apparatus, an
inspection method of a substrate with crystalized film and a
manufacturing method of a semiconductor device.
BACKGROUND ART
Patent Literature 1 discloses a laser annealing apparatus for
forming a polysilicon thin film. The laser annealing apparatus in
Patent Literature 1 irradiates a polysilicon thin film with
evaluating light to evaluate the crystalline state of the
polysilicon thin film. Then, the laser annealing apparatus detects
the irradiation light transmitted through the polysilicon thin
film. The crystalline state is evaluated based on the ratio of the
transmission intensity of the irradiation light to the light
intensity of reference light which is emitted from the same light
source and is not transmitted through the polysilicon thin
film.
CITATION LIST
Patent Literature
Patent Literature 1: Japanese Patent No. 2916452
SUMMARY OF INVENTION
Technical Problem
However, the laser annealing apparatus in Patent Literature 1
cannot properly evaluate a crystalline state.
Other problems and novel features will be clarified from the
description of this specification and the attached drawings.
Solution to Problem
According to an embodiment, an inspection method of a substrate
with a crystalized film, the method includes the steps of: (C)
detecting, by a photodetector, the probe beam transmitted through
the crystallized film; (D) changing an irradiation position of the
probe beam on the crystallized film to acquire a plurality of
detection values of a detection signal from the photodetector; and
(E) determining, based on a standard deviation of the plurality of
detection values, a crystalline state of the crystallized film.
According to an embodiment, manufacturing method of a semiconductor
device, the method includes the steps of: (b) irradiating the
amorphous film with a laser beam to crystallize the amorphous film
and to form a crystallized film; (c) irradiating the crystallized
film with a probe beam; (d) detecting, by a photodetector, the
probe beam transmitted through the crystallized film; (e) changing
an irradiation position of the probe beam on the crystallized film
to acquire a plurality of detection values of a detection signal
output from the photodetector; and (f) determining, based on a
standard deviation of the plurality of detection values, a
crystalline state of the crystallized film.
According to an embodiment, a laser annealing apparatus includes: a
laser beam source configured to emit a laser beam to crystallize an
amorphous film over a substrate and to form a crystallized film; a
probe beam source configured to emit a probe beam; a photodetector
configured to detect the probe beam transmitted through the
crystallized film; and a processing unit configured to change an
irradiation position of the probe beam on the substrate, to
calculate a standard deviation of detection values of a detection
signal output from the photodetector, and to determine a
crystalline state of the crystallized film based on the standard
deviation.
According to an embodiment, a laser annealing apparatus includes: a
stage configured to convey the substrate; a probe beam source
configured to emit a probe beam that enters the substrate outside
of the stage; and a photodetector configured to detect the probe
beam transmitted through the crystallized film outside the stage
during a conveying robot takes out the substrate from the
stage.
Advantageous Effects of Invention
According to the embodiment, it is possible to properly evaluate
the crystalline state of a crystallized film.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram showing an optical system of a laser annealing
apparatus according to the present embodiment.
FIG. 2 is a perspective view for explaining a laser beam and a
probe beam that enter a substrate in the laser annealing
apparatus.
FIG. 3 is a diagram for explaining a laser beam and a probe beam
that enter a substrate.
FIG. 4 is a diagram showing a probe beam that enters a
substrate.
FIG. 5 is a flowchart showing an inspection method according to an
embodiment.
FIG. 6 is a graph showing detection values in a condition-setting
substrate.
FIG. 7 is a graph showing the average values and the standard
deviations of detection values in a condition-setting
substrate.
FIG. 8 is a diagram showing the captured images and the standard
deviations of three substrates.
FIG. 9 is a flowchart showing a method for forming a polysilicon
film using an ELA apparatus according to the present
embodiment.
FIG. 10 is a diagram showing an apparatus layout including the ELA
apparatus according to the present embodiment.
FIG. 11 is a flowchart showing a method for forming a polysilicon
film using an ELA apparatus according to a comparison example.
FIG. 12 is a diagram showing an apparatus layout including the ELA
apparatus according to the comparison example.
FIG. 13 is a plan view schematically showing a configuration of an
ELA apparatus according to a second embodiment.
FIG. 14 is a side view schematically showing the configuration of
the ELA apparatus according to the second embodiment.
FIG. 15 is a diagram showing a configuration for a laser beam and a
probe beam to enter a substrate from the same side.
FIG. 16 is a cross-sectional view of a simplified configuration of
an organic EL display.
FIG. 17 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 18 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 19 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 20 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 20 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 22 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 23 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 24 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
FIG. 25 is a flowchart showing a method for determining the
optimized energy density of a laser beam in an inspection method
according to the present embodiment.
FIG. 26 is a diagram for explaining the region of the substrate in
the flowchart shown in FIG. 25.
FIG. 27 is a side view schematically showing the configuration of
the ELA apparatus according to a third embodiment.
FIG. 28 is a plan view schematically showing a configuration of an
ELA apparatus according to the third embodiment.
FIG. 29 is a diagram showing the size of a probe beam according to
a Z position.
FIG. 30 is a diagram showing an example of an optical system for a
probe beam in an ELA apparatus.
FIG. 31 is a diagram showing an example of an optical system for a
probe beam in an ELA apparatus.
FIG. 32 is a diagram showing an example of an optical system for a
probe beam in an ELA apparatus.
FIG. 33 is a graph showing a measurement result of a probe
beam.
DESCRIPTION OF EMBODIMENTS
First Embodiment
A laser annealing apparatus according to the present embodiment is,
for example, an excimer laser anneal (ELA) apparatus that forms low
temperature poly-silicon (LTPS) films. Hereinafter, a laser
annealing apparatus, and an inspection method and a manufacturing
method of a semiconductor device according to the present
embodiment are described with reference to the drawings.
(Optical system of ELA apparatus) A configuration of an ELA
apparatus 1 according to the present embodiment is described with
reference to FIG. 1. FIG. 1 is a diagram schematically showing an
optical system of the ELA apparatus 1. The ELA apparatus 1
irradiates a silicon film 101 formed on a substrate 100 with a
laser beam L1. This converts an amorphous silicon film (a-Si film)
101 into a polysilicon film (p-Si film) 101. The substrate 100 is,
for example, a transparent substrate such as a glass substrate.
Note that, an XYZ three-dimensional orthogonal coordinate system is
shown in FIG. 1 to clarify the description. The Z direction is the
vertical direction and perpendicular to the substrate 100. The XY
plane is parallel to the surface of the substrate 100 on which the
silicon film 101 is formed. The X direction is the longitudinal
direction of the rectangular substrate 100, and the Y direction is
the latitudinal direction of the substrate 100. In the ELA
apparatus 1, the silicon film 101 is irradiated with the laser beam
L1 while the substrate 100 is being conveyed in the +X direction
with a conveyance mechanism (not shown) such as a stage. With
regard to the silicon film 101 in FIG. 1, the silicon film 101
before the irradiation with the laser beam L1 is referred to as an
amorphous silicon film 101a, and the silicon film 101 after the
irradiation with the laser beam L1 is referred to as a polysilicon
film 101b.
The ELA apparatus 1 includes an annealing optical system 10, an
illumination optical system 20, and a detection optical system 30.
The annealing optical system 10 irradiates the silicon film 101
with the laser beam L1 for crystallizing the amorphous silicon film
101a. The illumination optical system 20 and the detection optical
system 30 evaluate ununiformity in the crystalline state of the
substrate 100.
Specifically, the ELA apparatus 1 includes a laser beam source 11,
a mirror 12, a projection lens 13, a probe beam source 21, a mirror
22, a lens 23, a condenser lens 24, a photodetector 25, and a
processing apparatus 26.
First, the annealing optical system 10 that irradiates the silicon
film 101 with the laser beam L1 is described. The annealing optical
system 10 is disposed above the substrate 100 (at the +Z side). The
laser beam source 11 is, for example, an excimer laser beam source
that emits an excimer laser beam having a center wavelength of 308
nm. The laser beam source 11 emits a pulsed laser beam L1. The
laser beam source 11 emits the laser beam L1 toward the mirror
12.
The mirror 12 and the projection lens 13 are disposed above the
substrate 100. The mirror 12 is a dichroic mirror that selectively
transmits light according to, for example, a wavelength. The mirror
12 reflects the laser beam L1.
The laser beam L1 is reflected by the mirror 12 and enters the
projection lens 13. The projection lens 13 includes a plurality of
lens for projecting the laser beam L1 on the substrate 100, that
is, on the silicon film 101.
The projection lens 13 condenses the laser beam L1 on the substrate
100. Here, the shape of an irradiation region P1 of the laser beam
L1 on the substrate 100 is described with reference to FIG. 2. The
laser beam L1 forms a linear irradiation region P1 along the Y
direction on the substrate 100. That is, the laser beam L1 is a
line beam having its longitudinal direction in the Y direction on
the substrate 100. The silicon film 101 is irradiated with the
laser beam L1 while the substrate 100 is being conveyed in the +X
direction. Thus, a belt-shaped region having the length of the
irradiation region P1 in the Y direction as its width can be
irradiated with the laser beam L1.
Next, the illumination optical system 20 that irradiates the
substrate 100 with a probe beam L2 is described with reference to
FIG. 1. The illumination optical system 20 is disposed under the
substrate 100 (at the -Z side). The probe beam source 21 emits a
probe beam L2 having a different wavelength from the laser beam L1.
For example, a continuous wave (CW) semiconductor laser beam source
or the like can be used as the probe beam source 21. The center
wavelength of the probe beam L2 is, for example, 401 nm. The
wavelength of the probe beam L2 is preferably a wavelength with a
low absorption rate at the silicon film 101. Thus, it is preferable
that a laser beam source, a light emitting diode (LED) light
source, or the like that emits monochromatic light is used as the
probe beam source 21.
The probe beam source 21 emits the probe beam L2 toward the mirror
22. The mirror 22 reflects the probe beam L2 toward the lens 23.
The lens 23 condenses the probe beam L2 on the silicon film 101. As
shown in FIG. 2, a cylindrical lens can be used as the lens 23.
Accordingly, the probe beam L2 forms a linear illumination region
P2 along the Y direction on the substrate 100 (the silicon film
101). That is, the probe beam L2 is a line beam having its
longitudinal direction in the Y direction on the substrate 100. In
addition, the length of the illumination region P2 in the Y
direction is shorter than the irradiation region P1.
The illumination region P2 of the probe beam L2 is disposed at the
+X side compared to the irradiation region P1 of the laser beam L1.
That is, the probe beam L2 enters the substrate 100 at an upper
stream side in the conveying direction of the substrate 100 than
the irradiation region P1 of the laser beam L1. Accordingly, the
crystallized polysilicon film 101b is irradiated with the probe
beam L2 as shown in FIG. 1.
Next, the detection optical system 30 that guides a probe beam L3
transmitted through the silicon film 101 to the photodetector 25 is
described. The detection optical system 30 is disposed above the
substrate 100. Note that, FIG. 1 shows the probe beam transmitted
through the silicon film 101 as the probe beam L3. The
transmittance of the silicon film 101 to a probe beam varies
according to the crystalline state of silicon.
The probe beam L3 transmitted through the silicon film 101 enters
the projection lens 13. The probe beam L3 refracted by the
projection lens 13 enters the mirror 12. Note that, the mirror 12
is a dichroic mirror that transmits or reflects light according to
a wavelength as described above. The mirror 12 transmits the probe
beam L3 having the wavelength of 401 nm and reflects the laser beam
L1 having the wavelength of 308 nm. Thus, the probe beam L3 is
branched from the optical path of the laser beam L1. The mirror 12
serves as a light branching means for branching the optical path of
the laser beam L1 and the optical path of the probe beam L3
according to a wavelength.
The probe beam L3 having passed through the mirror 12 enters the
condenser lens 24. The condenser lens 24 condenses the probe beam
L3 on the light-receiving surface of the photodetector 25. The
photodetector 25 is, for example, a photo diode and detects the
probe beam L3. The photodetector 25 outputs a detection signal
according to the detection light amount of the probe beam L3 to the
processing apparatus 26. The detection value of the detection
signal corresponds to the transmittance of the silicon film 101. In
addition, since the substrate 100 is conveyed in the +X direction
at a constant speed, the photodetector 25 detects the profile of
the detection light amount in the X direction (that is, the
transmittance of the silicon film 101).
The processing apparatus 26 is an operation unit that performs
predetermined operation to the detection value of the detection
signal. Note that, the processing apparatus 26 may includes an A/D
converter that A/D-converts an analogue detection signal into a
digital detection value. Alternatively, the photodetector 25 may
includes an A/D converter that A/D-converts an analogue detection
signal into a digital detection value.
While scanning the substrate 100 in the +X direction, the
photodetector 25 detects the probe beam L3. Thus, the processing
apparatus 26 acquires a plurality of detection values according to
the sampling rate of the photodetector 25 or the A/D converter. The
processing apparatus 26 includes a memory that stores the detection
values. Since the substrate 100 is scanned in the +X direction at a
constant speed, the detection values indicate the profile of the
transmittance in the X direction. If the crystalline state of the
silicon film 101 is ununiform, different detection values according
to the illumination positions are acquired. If the crystalline
state of the silicon film 101 is uniform, the detection values are
substantially the same value.
The processing apparatus 26 determines the quality of the substrate
100 based on the standard deviation of the detection values. That
is, when the standard deviation is less than a preset threshold,
the processing apparatus 26 determines that the ununiformity in the
crystalline state is small. In this case, the processing apparatus
26 that the polysilicon film 101b is formed uniformly and that the
substrate 100 is non-defective. On the other hand, when the
standard deviation is equal to or greater than the preset
threshold, the processing apparatus 26 determines that the
ununiformity in the crystalline state is large. In this case, the
processing apparatus 26 determines that the polysilicon film with
large ununiformity is formed and that the substrate 100 is
defective. The processing of the processing apparatus 26 is to be
described later.
With reference to FIGS. 3 and 4, the illumination region P2 of the
probe beam L2 on the substrate 100 is described. FIG. 3 is an XY
plan view showing examples of the illumination region P2 of the
probe beam L2 and the irradiation region P1 of the laser beam L1.
FIG. 4 shows the probe beam L2 measured by a beam profiler.
As shown in FIG. 3, the width of the irradiation region P1 in the X
direction is 400 In addition, a gap of 100 .mu.m is provided
between the irradiation region P1 and the illumination region P2 in
the X direction. The length of the irradiation region P1 in the Y
direction is longer than the length of the illumination region P2.
As shown in FIG. 4, the length of the illumination region P2 in the
Y direction is 6 mm. The maximum width of the illumination region
P2 in the X direction is 17 Note that, when the irradiation region
P1 is smaller than the size of the substrate 100 in the Y
direction, the substrate 100 is moved in the Y direction to perform
annealing treatment. Accordingly, a silicon film 100 is
crystallized on the entire substrate 100.
Here, it is assumed that the conveyance speed of the substrate 100
in the X direction is 12 mm/sec. Furthermore, it is assumed that
the condensed size of the illumination region P2 is 17 .mu.m, and
that the measurement overlap is set to 50% (=8.5 .mu.m). The
sampling rate required in this case is 12000/8.5=1.411 kHz. Note
that, the measurement overlap defines the size of the overlapped
illumination region P2 between the two consecutive detection
values. That is, the region overlapped by 8.5 .mu.m is irradiated
with the illumination region P2 corresponding to the first
detection value and the illumination region P2 corresponding to the
second detection value.
Next, an inspection method according to the present embodiment is
described with reference to FIG. 5. FIG. 5 is a flowchart showing
the inspection method according to the present embodiment.
First, when annealing treatment is performed to the silicon film
101, the processing apparatus 26 acquires n numbers of detection
values V.sub.1, V.sub.2, . . . , V.sub.n (S11). Here, n is an
integer of 2 or more. As the illumination position of the probe
beam L2 is changed in the X direction, the detection values V.sub.1
to V.sub.n are detected. For example, the detection value when the
illumination position on the substrate 100 in the X direction is
X.sub.1 is V.sub.1, and the detection value when the illumination
position on the substrate 100 in the X direction is X.sub.2 is
V.sub.2. The detection value when the illumination position on the
substrate 100 in the X direction is X.sub.n is V.sub.n. In this
manner, the photodetector 25 detects a detection value according to
an illumination position in the X direction. As the illumination
position onto the substrate 100 is changed by the substrate
conveyance, the processing apparatus 26 acquires the detection
values V.sub.1 to V.sub.n.
Then, the processing apparatus 26 calculates an average value
V.sub.average and a standard deviation .sigma. of the detection
values V.sub.1 to V.sub.n (S12). Specifically, a processor or an
operation circuit provided to the processing apparatus 26
calculates the average value V.sub.average and the standard
deviation .sigma. based on the expressions shown in FIG. 5.
The processing apparatus 26 determines whether the calculated
standard deviation .sigma. is less than a threshold
.sigma..sub..alpha. (S13). That is, the processing apparatus 26
compares the standard deviation .sigma. with the preset threshold
.sigma..sub..alpha.. Then, when the standard deviation .sigma. is
less than the threshold .sigma..sub..alpha. (YES in S13), the
processing apparatus 26 determines the substrate 100 to be
non-defective, and the treatment is terminated. On the other hand,
when the standard deviation .sigma. is equal to or greater than the
threshold .sigma..sub..alpha. (NO in S13), the processing apparatus
26 determines the substrate 100 to be defective, and returns to the
annealing treatment. Accordingly, re-annealing treatment is
performed to the defective substrate 100.
In the re-annealing treatment, the entire surface of the substrate
100 is irradiated with the laser beam L1 similarly to the first
annealing treatment. In the re-annealing treatment, the substrate
100 is irradiated with the laser beam L1 having a weaker
irradiation intensity than that in the first annealing treatment.
The portion where the irradiation light amount of the laser beam L1
has been insufficient to be adequately crystallized can be
certainly crystallized. In addition, the photodetector 25 may
detect the probe beam L3, and the processing apparatus 26 may
determine the crystalline state similarly in the re-annealing
treatment.
Furthermore, the substrate 100 may be partially irradiated with the
laser beam L1 in the re-annealing treatment. It is thereby possible
to shorten the time required for the re-annealing treatment. For
example, the measurement range is divided into ten, and the
processing apparatus 26 calculates ten standard deviations
.sigma..sub.1 to .sigma..sub.10. Then, the portions having large
standard deviations among the standard deviations .sigma..sub.1 to
.sigma..sub.10 may be irradiated with the laser beam L1. For this
reason, the processing apparatus 26 compares each of the standard
deviations .sigma..sub.1 to .sigma..sub.10 with the threshold
.sigma..sub..alpha. to obtain the portions having standard
deviations greater than the threshold .sigma..sub..alpha.. Then,
the portions having the standard deviations greater than the
threshold .sigma..sub..alpha. are irradiated with the laser beam
L1. In other words, the portions having the standard deviations
less than the threshold .sigma..sub..alpha. are not irradiated with
the laser beam L1. It is obvious that the number of divisions of
the substrate 100 is not limited to ten, and the number is only
required to be two or more.
In the present embodiment, the quality determination based on the
average value V.sub.average is performed in S13 in addition to the
quality determination based on the standard deviation G. That is,
the average value is added to the evaluation items as well as the
standard deviation. Then, when either of the standard deviation or
the average value does not meet the criterion, the processing
apparatus 26 determines the substrate 100 to be defective. Note
that, the quality determination based on the average value
V.sub.average may not be performed. In this case, the processing
apparatus 26 is only required to calculate the standard deviation
.sigma. without calculating the average value V.sub.average in step
S12.
Specifically, it is determined whether the average value
V.sub.average is less than a threshold V.sub..alpha. (S13). That
is, the processing apparatus 26 compares the average value
V.sub.average with the preset threshold V.sub..alpha.. Then, when
the average value V.sub.average is greater than the threshold
V.sub..alpha. (YES in S13), the processing apparatus 26 determines
the substrate 100 to be non-defective and terminates the treatment.
On the other hand, when the average value V.sub.average is equal to
or less than the threshold V.sub..alpha. (YES in S13), the
processing apparatus 26 determines the substrate 100 to be
defective and returns to the annealing treatment. In this manner,
by performing the quality determination based on both of the
standard deviation .sigma. and the average value V.sub.average, it
is possible to more properly evaluate the crystalline state. Thus,
it is possible to improve the accuracy of the quality
determination. Then, the laser annealing apparatus 1 performs
re-annealing treatment to the substrate 100 determined to be
defective. Accordingly, it is possible to certainly crystallize the
portion where the irradiation light amount of the laser beam L1 has
been insufficient to be adequately crystallized. Thus, it is
possible to improve the ununiformity in the crystalline state.
In this manner, the photodetector 25 detects the probe beam L3
transmitted through the substrate 100 in the present embodiment.
Since the probe beam L3 is detected at different illumination
positions by the photodetector 25, the processing apparatus 26
acquires a plurality of detection values. The processing apparatus
26 performs the quality determination based on the standard
deviation of the detection values. It is thereby possible to
properly evaluate ununiformity in the polysilicon film 101b. Thus,
it is possible to further improve the accuracy of the quality
determination. Especially when the laser beam L1 is a linear pulsed
laser beam, stripes of light and darkness along the line (also
referred to as shot unevenness) can appear on the silicon film 101.
It is possible for the ELA apparatus 1 according to the present
embodiment to reduce the shot unevenness.
In the present embodiment, by adding not only the standard
deviation .sigma. of the detection values but also the average
value V.sub.average to the evaluation items, it is possible to
further improve the accuracy of the quality determination. In
addition, the re-annealing treatment is performed to the substrate
100 determined to be defective. It is possible to certainly
crystallize the portion where the irradiation light amount of the
laser beam L1 has been insufficient to be adequately crystallized.
Thus, it is possible to improve the yield and to increase the
productivity.
Furthermore, while a substrate is being conveyed by a stage or the
like, the substrate 100 is irradiated simultaneously with the laser
beam L1 and the probe beam L2. It is thereby possible to detect the
probe beam L3 transmitted through the silicon film 101 during laser
annealing. Thus, it is possible to determine whether the state of
the surface of the silicon film 101 is optimal in a short time.
In the present embodiment, the illumination region P2 of the probe
beam L2 is disposed in the vicinity of the irradiation region P1 of
the laser beam L1. Accordingly, it is possible to evaluate the
crystalline state of the silicon film 101 immediately after being
crystallized. Thus, it is possible to evaluate ununiformity in the
crystalline state of the silicon film 101 substantially on time and
to improve the accuracy of the quality determination.
In addition, the photodetector 25 detects the probe beam having
passed through the projection lens 13 in order to bring the
illumination region P2 of the probe beam L2 closer to the
irradiation region P1 of the laser beam L1. In other words, the
projection lens 13 is disposed in the optical path from the probe
beam source 21 to the photodetector 25. The projection lens 13 is
shared by the annealing optical system 10 and the illumination
optical system 20. Accordingly, it is possible to bring the
illumination region P2 closer to the irradiation region P1 on the
substrate 100.
In the present embodiment, the substrate 100 is irradiated with the
linear illumination region P2. Thus, it is possible to reduce the
influence of small dirt, dust, or the like. For example, in the
case of the irradiation with a point-like illumination region, if
dirt or the like is attached to the illumination region, the
transmittance is greatly lowered. In this case, the detection value
at the portion to which the dirt or the like is attached is greatly
lowered, and the standard deviation becomes larger. On the other
hand, by the irradiation with the linear illumination region P2 as
described in the present embodiment, it is possible to reduce the
influence of small dirt or the like. That is, since the region
having a wide width in the Y direction is irradiated, it is
possible to improve the accuracy of the quality determination
compared with the irradiation with a point-like illumination
region. Furthermore, since the illumination region P2 is parallel
to the linear irradiation region P1, it is possible to properly
evaluate shot unevenness which is stripes of light and darkness
along the Y direction.
In the present embodiment, the condenser lens 24 is disposed in
front of the photodetector 25. The condenser lens 24 condenses the
probe beam L3 on the light-receiving surface of the photodetector
25. That is, the probe beam L3 forms a point-like spot on the
light-receiving surface of the photodetector 25. Thus, it is
possible to use a diode having a small light-receiving region as
the photodetector 25. Accordingly, it is not necessary to use a
camera in which light-receiving pixels are arranged in an array or
the like as the photodetector 25. Furthermore, it is out necessary
to perform image processing to images by the camera. Thus, it is
possible to simplify the configuration and the processing of the
apparatus.
(Measurement Result)
FIG. 6 shows a measurement result of the probe beam L3. FIG. 6 is a
graph showing a measurement result in a condition-setting
substrate. The graph shows the measurement result of the probe beam
L3 when the irradiation intensity of the laser beam L1 to one
substrate 100 is changed. Specifically, the substrate 100 is
divided into 21 regions T80 to T100 as shown in FIG. 6, and the
irradiation intensity of the laser beam L1 is changed at each
region. The irradiation intensity is gradually increased from the
region T80 toward the region T100. Specifically, the numeral
representing each region means the irradiation intensity when the
irradiation intensity at the region T100 is set to 100. For
example, the region T80 means the 80% irradiation intensity of the
region T100, and the region T81 means the 81% irradiation intensity
of the region T100. Note that, the irradiation intensity at each
region is constant. The vertical axis indicates a detection value
of a detection signal of the photodetector 25. The detection value
in this graph corresponds to the voltage [V] of the detection
signal output from the photodetector 25.
FIG. 7 shows the average value and the standard deviation .sigma.
of the detection values V at each region. It is assumed that the
characteristic of the silicon film 101 is more excellent as the
detection values V are smaller. In this case, the region having the
smallest average value is the region T95, but the region having the
smallest standard deviation .sigma. is the region T85. Thus, the
irradiation intensity at the region T85 can be the optimized
irradiation intensity. In other words, the average value is small
but the variation of the detection value is large at the region
T95, and the standard deviation is large. For this reason,
ununiformity in the crystalline state is increased, and a defective
rate can be increased. By performing the annealing treatment using
the laser beam L1 having the irradiation intensity at the region
T85, it is possible to form the polysilicon film 101b having a
uniform crystalline state.
FIG. 8 is a diagram showing images of the substrate 100 captured by
a camera and measurement results by the photodetector 25. FIG. 8
shows three substrate 100 as substrates I to III, and the
irradiation intensity of the laser beam L1 to each substrate is
changed. In addition, each of the substrates I to III is irradiated
with the laser beam L1 having the constant irradiation intensity.
The captured images are shown at the upper part of FIG. 8, and the
detection values (voltage values) are shown at the lower part. FIG.
8 shows that the detection values vary in the substrates I and III
the images of which have large uneven brightness. On the other
hand, the variation in the detection values is small in the
substrate II the image of which has small uneven brightness. In
this manner, by performing inspection based on the standard
deviation of the detection values, it is possible to improve the
accuracy of the quality determination.
(Method for Forming Polysilicon Film) In the present embodiment,
since the ELA apparatus 1 has a function of quality determination,
it is possible to further increase the productivity. This point is
described with reference to FIGS. 9 and 10. FIG. 9 is a flowchart
showing a method for forming a polysilicon film using the ELA
apparatus 1. More specifically, FIG. 9 shows a forming method when
a substrate is determined to be defective by the inspection method
according to the present embodiment. FIG. 10 is a diagram showing
an apparatus layout for the ELA apparatus 1 and a cleaning
apparatus 3 in a manufacturing factory.
First, the ELA apparatus 1 performs the annealing treatment and the
quality determination (S101). Specifically, a transfer robot 4
takes out the substrate 100 with an amorphous silicon film cleaned
by the cleaning apparatus 3 from a cassette 5. Then, the transfer
robot 4 carries the substrate 100 in the ELA apparatus 1. Note
that, the transfer robot 4 includes two hands and can hold the
substrate 100 to be carried in each apparatus and the substrate 100
to be carried out of each apparatus at the same time.
Then, the substrate 100 is irradiated with the laser beam L1 and
the probe beam L2 while the substrate 100 is being conveyed as
shown in FIG. 1 and the like. For example, by driving a stage or
the like to convey the substrate 100, the annealing treatment and
the quality determination are performed. Since the substrate 100 is
irradiated simultaneously with the laser beam L1 and the probe beam
L2, the annealing treatment and the quality determination are
finished substantially at the same time. Since the photodetector 25
detects the probe beam L3 while the substrate 100 is being
conveyed, the processing apparatus 26 acquires a plurality of
detection values. Then, when the processing apparatus 26 determines
the substrate 100 to be defective based on the standard deviation
.sigma. of the detection values, the re-annealing treatment is
performed (S102). Here, steps S101 and S102 are performed in the
same ELA apparatus 1. That is, it is possible to perform steps S101
and S102 without carrying the substrate 100 out of the ELA
apparatus 1.
Next, a method for forming a polysilicon film using an ELA
apparatus according to a comparison example is described with
reference to FIGS. 11 and 12. FIG. 11 is a flowchart showing a
method for forming a polysilicon film using an ELA apparatus 201
according to a comparison example. FIG. 12 is a diagram showing a
layout for the ELA apparatus 201, a cleaning apparatus 203, and an
inspection apparatus 202 in a manufacturing factory. Note that, the
ELA apparatus 201 according the comparison example does not have a
function of quality determination. Thus, the inspection apparatus
202 is disposed in the vicinity of the ELA apparatus 201 and the
cleaning apparatus 203. The inspection apparatus 202 performs the
quality determination for the substrate 100.
First, the ELA apparatus 201 performs laser annealing treatment
(S201). Specifically, a transfer robot 204 takes out the substrate
100 with an amorphous silicon film cleaned by the cleaning
apparatus 203 from a cassette 205. Then, the transfer robot 204
carries the substrate 100 in the ELA apparatus 201. Then, the ELA
apparatus 201 performs annealing treatment.
When the annealing treatment is finished, the transfer robot 204
carries the substrate 100 subjected to the annealing treatment out
of the ELA apparatus (S202). When a mobile robot 204 that has
carried the substrate 100 out moves before the inspection apparatus
is carried in (S204), the transfer robot 204 carries the substrate
100 in the inspection apparatus 202 (S205).
The inspection apparatus 202 performs the quality determination for
the carried-in substrate 100 (S206). Here, an example in which the
substrate 100 is determined to be defective is described. The
transfer robot 204 carries the substrate 100 out of the inspection
apparatus 202 (S207). When the transfer robot 204 that has carried
the substrate 100 out moves before the ELA apparatus 201 is carried
in (S209), the transfer robot 204 carries the substrate 100 in the
ELA apparatus 201 (S210). Then, the ELA apparatus 201 performs
re-annealing treatment to the substrate 100 determined to be
defective (S211).
In this manner, since the ELA apparatus 201 according to the
comparison example does not have a function of quality
determination, the number of times of carrying-in and carrying-out
of the substrate 100 is increased. That is, the substrate 100 is
required to be carried in and carried out of the inspection
apparatus 202. This makes tact time longer, and it is difficult to
improve the productivity. In addition, a cleaning process by the
cleaning apparatus 203 can be required between the quality
determination process by the inspection apparatus 202 (S206) and
the re-annealing treatment S211 by the ELA apparatus 201. In this
case, the number of times of carrying-in and carrying-out of the
substrate 100 is further increased, and the productivity is
lowered.
In other words, it is possible for the ELA apparatus 1 according to
the present embodiment to manufacture the substrate 100 with a
polysilicon film with high productivity. That is, since the number
of times of carrying-in and carrying-out of the substrate 100 is
reduced, it is possible to finish the treatment in a short time.
Furthermore, since the annealing treatment and the quality
determination are performed in the same ELA apparatus 1, it is not
necessary to perform a cleaning process between the quality
determination and the re-annealing treatment. Accordingly, it is
possible to reduce the number of times of carrying-in and
carrying-out of the substrate 100 and to improve the productivity.
In addition, it is possible to evaluate the polysilicon film 101b
immediately after the irradiation with the laser beam L1. Thus, it
is possible to feed back the condition, such as transmittance, for
the next substrate 100 and to perform laser irradiation under an
appropriate condition.
Second Embodiment
An ELA apparatus 40 according to the present embodiment is
described with reference to FIGS. 13 and 14. FIG. 13 is a plan view
schematically showing a configuration of the ELA apparatus 40. FIG.
14 is a side view schematically showing the configuration of the
ELA apparatus 40. The configuration of the apparatus is
appropriately simplified in FIGS. 13 and 14. In the present
embodiment, a function of quality determination is added to the ELA
apparatus 40 provided with a gas-floating unit.
The ELA apparatus 40 includes a treatment room 41, a continuous
conveying path 42, gas-floating units 43a and 43b, a suction part
44, and an opening 45. The treatment room 41 includes a carrying-in
port 41a and a carrying-out port 41b. The ELA apparatus 40
includes, similarly to the first embodiment, an annealing optical
system 10, an illumination optical system 20, and a detection
optical system 30.
The ELA apparatus 40 according to the present embodiment is
provided with the gas-floating units 43a and 43b that float a
substrate 100 in the treatment room 41 in which annealing treatment
is performed. Note that, the basic configuration except for the
gas-floating units 43a and 43b is similar to the ELA apparatus 1
described in the first embodiment, and the description is
appropriately omitted. For example, the optical system of the ELA
apparatus 40 according to the present embodiment is substantially
similar to that of the ELA apparatus 1 according to the first
embodiment. However, a probe beam L3 enters a condenser lens 24
without passing through a mirror 12. In this case, a reflex mirror
that reflects almost all incident light can be used as the mirror
12 instead of a dichroic mirror.
The treatment room 41 of the ELA apparatus 40 has a
rectangular-parallelepiped wall part. The carrying-in port 41a (-X
side) and the carrying-out port 41b (+X side) are provided on the
walls facing in the longitudinal direction (the X direction) of the
treatment room 41. Each of the carrying-in port 41a and the
carrying-out port 41b may be opened or have an openable structure.
The openable structure can be a simple sealing structure. Note
that, the setting positions of the carrying-in port 41a and the
carrying-out port 41b are only required to be along the conveying
direction, and not limited to specific positions.
In the treatment room 41, the continuous conveying path 42 is
provided from the carrying-in port 41a to the carrying-out port
41b. The gas-floating units 43a and 43b are disposed at the
continuous conveying path 42. The gas-floating unit 43a is disposed
at the carrying-in port 41a side, and the gas-floating unit 43b is
disposed at the carrying-out port 41b side. The opening 45 is
provided between the gas-floating unit 43a and the gas-floating
unit 43b. The opening 45 corresponds to an irradiation region P1 at
which laser annealing is performed.
The gas-floating units 43a and 43b are floating stages that jet gas
upward from below, and float and support the substrate 100 over
themselves. Note that, the gas-floating units 43a and 43b each have
a plurality of jetting points (not shown) to adjust the posture and
bending of the substrate 100.
As shown in FIG. 14, the part at which the gas-floating unit 43a is
provided in the continuous conveying path 42 is referred to as a
carrying-in conveying path 42a, and the part at which the
gas-floating unit 43b is provided is referred to as a carrying-out
conveying path 42b. In addition, the part corresponding to the
opening 45 in the continuous conveying path 42 is referred to as an
irradiation-region conveying path 42c.
The suction part 44 sucks the end portion of the substrate 100. The
suction part 44 is moved along a guide rail (not shown) in the X
direction while the suction part 44 is sucking the substrate 100.
It is thereby possible to covey the substrate 100 in the +X
direction.
The substrate 100 carried in from the carrying-in port 41a is
conveyed in the order of the carrying-in conveying path 42a, the
irradiation-region conveying path 42c, and the carrying-out
conveying path 42b. Then, when conveyed to the end of the
carrying-out conveying path 42b, the substrate 100 is carried out
of the carrying-out port 41b. Specifically, the substrate 100
carried in from the carrying-in port 41a is floated by the gas from
the gas-floating unit 43a. A floating substrate 1000 is conveyed in
the +X direction (for example, a substrate 100a in FIG. 14). Then,
when the substrate 100 reaches an illumination-region conveying
path 42c, the annealing treatment and detection of a probe beam are
performed (for example, a substrate 100b in FIG. 14).
At this time, the substrate 100 is irradiated with a laser beam L1
and a probe beam L2 at the opening 45 in the irradiation-region
conveying path 42c. Thus, the illumination optical system 20 is
disposed so that the probe beam L2 passes through the opening 45.
For example, a lens 23 is disposed directly under the opening 45.
In this manner, the probe beam L2 passes through the opening 45
disposed between the gas-floating unit 43a and the gas-floating
unit 43b. That is, an illumination region P2 of the probe beam L2
is positioned in the irradiation-region conveying path 42c.
Then, the substrate 100 reaches the carrying-out conveying path
42b, the substrate 100 is floated by the gas from both of the
gas-floating unit 43a and the gas-floating unit 43b. When the end
of the substrate 100 passes the carrying-in conveying path 42a, the
substrate 100 is floated by the gas from the gas-floating unit 43b
(for example, a substrate 100c in FIG. 14).
An inspection method according to the present embodiment is
suitable for the ELA apparatus 40 including a plurality of
gas-floating units of the gas-floating units 43a and 43b. For
example, the opening 45 is normally provided over the entire
substrate 100 in the Y direction (see FIG. 13). Thus, it is
possible for the ELA apparatus 40 according to the present
embodiment to form the illumination region P2 at an arbitrary
position in the Y direction. Accordingly, it is possible to form
the illumination region P2 at, for example, the center of the
substrate 100 in the Y direction. Thus, it is possible to evaluate
the crystalline state at the center of the substrate 100 in the Y
direction and to improve the accuracy of the quality
determination.
Note that, the illumination optical system 20 is disposed under the
substrate 100, and the detection optical system 30 is disposed
above the substrate 100 in the first and second embodiments, but
the positions of the illumination optical system 20 and the
detection optical system 30 may be inverted. That is, the
illumination optical system 20 can be disposed above the substrate
100, and the detection optical system 30 can be disposed under the
substrate 100. In this case, the lens 23 is disposed at the +Z side
of the substrate 100 as shown in FIG. 15. In second embodiment, the
probe beam transmitted through the substrate 100 passes through the
opening 45. In addition, when the illumination optical system 20 is
disposed above the substrate 100 and the detection optical system
30 is disposed under the substrate 100, the probe beam L2 may be
condensed with a lens different from the projection lens 13.
(Organic EL display) A semiconductor device having the above
polysilicon film is suitable for a thin film transistor (TFT) array
substrate used for an organic electro luminescence (EL) display.
That is, the polysilicon film is used as a semiconductor layer
having a source region, a channel region, and a drain region of a
TFT.
Hereinafter, a case in which a semiconductor device according to
the present embodiment is used for an organic EL display is
described. FIG. 16 is a cross section of a pixel circuit of the
organic EL display which is illustrated in a simplified manner. The
organic EL display device 300 shown in FIG. 16 is an
active-matrix-type display device in which a TFT is disposed in
each pixel PX.
The organic EL display device 300 includes a substrate 310, a TFT
layer 311, an organic layer 312, a color filter layer 313, and a
sealing substrate 314. FIG. 14 shows a top-emission-type organic EL
display device, in which the side of the sealing substrate 314 is
located on the viewing side. Note that the following description is
given to show an example of a configuration of an organic EL
display device and this embodiment is not limited to the
below-described configuration. For example, a semiconductor device
according to this embodiment may be used for a bottom-emission-type
organic EL display device.
The substrate 310 is a glass substrate or a metal substrate. The
TFT layer 311 is provided on the substrate 310. The TFT layer 311
includes TFTs 311a disposed in the respective pixels PX. Further,
the TFT layer 311 includes wiring lines (not shown) connected to
the TFTs 311a, and the like. The TFTs 311a, the wiring lines, and
the like constitute pixel circuits.
The organic layer 312 is provided on the TFT layer 311. The organic
layer 312 includes an organic EL light-emitting element 312a
disposed in each pixel PX. The organic EL light-emitting element
312a has, for example, a laminated structure in which an anode, a
hole injection layer, a hole transport layer, a light-emitting
layer, an electron transport layer, an electron injection layer,
and a cathode are laminated. In the case of the top emission type,
the anode is a metal electrode and the cathode is a transparent
conductive film made of ITO (Indium Tin Oxide) or the like.
Further, in the organic layer 312, separation walls 312b for
separating organic EL light-emitting elements 312a are provided
between pixels PX.
The color filter layer 313 is provided on the organic layer 312.
The color filter layer 313 includes color filters 313a for
performing color displaying. That is, in each pixel PX, a resin
layer colored in R (red), G (green), or B (blue) is provided as the
color filter 313a. When white light emitted from the organic layer
312 passes through the color filters 313a, the white light is
converted into light having RGB colors. Note that in the case of a
three-color system in which organic EL light-emitting elements
capable of emitting each color of RGB are provided in the organic
layer 312, the color filter layer 313 may be unnecessary.
The sealing substrate 314 is provided on the color filter layer
313. The sealing substrate 314 is a transparent substrate such as a
glass substrate and is provided to prevent deterioration of the
organic EL light-emitting elements of the organic layer 312.
Electric currents flowing through the organic EL light-emitting
elements 312a of the organic layer 312 are changed by display
signals supplied to the pixel circuits. Therefore, it is possible
to control an amount of light emitted in each pixel PX by supplying
a display signal corresponding to a display image to each pixel PX.
As a result, it is possible to display a desired image.
In an active matrix display device such as an organic EL display,
one pixel PX is provided with one or more TFTs (for example, a
switching TFT and a driving TFT). Then, the TFT of each pixel PX is
provided with a semiconductor layer having a source region, a
channel region, and a drain region. The polysilicon film according
to the present embodiment is suitable for a semiconductor layer of
a TFT. That is, by using the polysilicon film manufactured by the
above manufacturing method for a semiconductor layer of a TFT array
substrate, it is possible to suppress in-plane ununiformity which
is the TFT characteristics. Thus, it is possible to manufacture a
display device having an excellent display characteristic with high
productivity.
(Manufacturing Method of Semiconductor Device)
A manufacturing method of a semiconductor device using the ELA
apparatus according to the present embodiment is suitable for
manufacturing a TFT array substrate. The manufacturing method of a
semiconductor device having a TFT is described with reference to
FIGS. 17 to 24. FIGS. 17 to 24 are cross-sectional views showing
processes for manufacturing a semiconductor device. In the
following description, a manufacturing method of a semiconductor
device having an inverted staggered TFT is described.
First, as shown in FIG. 17, a gate electrode 402 is formed on a
glass substrate 401. Note that, the glass substrate 401 corresponds
to the above substrate 100. As the gate electrode 402, for example,
a metal thin film containing aluminium can be used. A metal thin
film is formed on the glass substrate 401 by a sputtering method or
a deposition method. Then, the metal thin film is patterned by
photolithography to form the gate electrode 402. In a
photolithography method, processing, such as resist coating,
exposure, developing, etching, and resist stripping, is performed.
Note that, various types of wiring may be formed in the same
process as the patterning of the gate electrode 402.
Next, a gate insulating film 403 is formed on the gate electrode
402 as shown in FIG. 18. The gate insulating film 403 is formed so
as to cover the gate electrode 402. Then, an amorphous silicon film
404 is formed on the gate insulating film 403 as shown in FIG. 19.
The amorphous silicon film 404 is arranged so as to overlap the
gate electrode 402 interposing the gate insulating film 403.
The gate insulating film 403 is a silicon nitride film (SiN.sub.x)
or a silicon oxide film (SiO.sub.2 film), or a lamination film
thereof, or the like. Specifically, the gate insulating film 403
and the amorphous silicon film 404 are continuously formed by a
chemical vapor deposition (CVD) method.
Then, the amorphous silicon film 404 is irradiated with the laser
beam L1 to form a polysilicon film 405 as shown in FIG. 20. That
is, the amorphous silicon film 404 is crystallized by the ELA
apparatus 1 shown in FIG. 1 and the like. The polysilicon film 405
with silicon crystallized is thereby formed on the gate insulating
film 403. The polysilicon film 405 corresponds to the above
polysilicon film 101b.
At this time, the polysilicon film 405 is inspected by the
inspection method according to the present embodiment. When the
polysilicon film 405 does not meet a predetermined criterion, the
polysilicon film 405 is irradiated with a laser beam again. Thus,
it is possible to further uniformize the characteristic of the
polysilicon film 405. Since the in-plane ununiformity can be
suppressed, it is possible to manufacture a display device having
an excellent display characteristic with high productivity.
Note that, although not shown, the polysilicon film 405 is pattered
by a photolithography method. In addition, impurities may be
introduced into the polysilicon film 405 by an ion implantation
method or the like.
Then, an interlayer insulating film 406 is formed on the
polysilicon film 405 as shown in FIG. 21. The interlayer insulating
film 406 is provided with contact holes 406a for exposing the
polysilicon film 405.
The interlayer insulating film 406 is a silicon nitride film
(SiN.sub.x) or a silicon oxide film (SiO.sub.2 film), or a
lamination film thereof, or the like. Specifically, the interlayer
insulating film 406 is formed by a chemical vapor deposition (CVD)
method. Then, the interlayer insulating film 406 is patterned by a
photolithography method to form the contact holes 406a.
Next, a source electrode 407a and a drain electrode 407b are formed
on the interlayer insulating film 406 as shown in FIG. 22. The
source electrode 407a and the drain electrode 407b are formed so as
to cover the contact holes 406a. That is, the source electrode 407a
and the drain electrode 407b are formed from the inside of the
contact holes 406a over the interlayer insulating film 406. Thus,
the source electrode 407a and the drain electrode 407b are
electrically connected to the polysilicon film 405 though the
contact holes 406a.
Accordingly, a TFT 410 is formed. The TFT 410 corresponds to the
above TFT 311a. The region overlapping the gate electrode 402 in
the polysilicon film 405 is a channel region 405c. The source
electrode 407a side of the polysilicon film 405 from the channel
region 405c is a source region 405a, and the drain electrode 407b
side is a drain region 405b.
The source electrode 407a and the drain electrode 407b are formed
of a metal thin film containing aluminium. A metal thin film is
formed on the interlayer insulating film 406 by a sputtering method
or a deposition method. Then, the metal thin film is patterned by
photolithography to form the source electrode 407a and the drain
electrode 407b. Note that, various types of wiring may be formed in
the same process as the patterning of the source electrode 407a and
the drain electrode 407b.
Then, a planarization film 408 is formed on the source electrode
407a and the drain electrode 407b as shown in FIG. 23. The
planarization film 408 is formed so as to cover the source
electrode 407a and the drain electrode 407b. The planarization film
408 is provided with a contact hole 408a for exposing the drain
electrode 407b.
The planarization film 408 is formed of, for example, a
photosensitive resin film. A photosensitive resin film is coated on
the source electrode 407a and the drain electrode 407b, and exposed
and developed. Accordingly, it is possible to pattern the
planarization film 408 having the contact hole 408a.
Then, a pixel electrode 409 is formed on the planarization film 408
as shown in FIG. 24. The pixel electrode 409 is formed so as to
cover the contact hole 408a. That is, the pixel electrode 409 is
formed from the inside of the contact hole 408a over the
planarization film 408. Thus, the pixel electrode 409 is
electrically connected to the drain electrode 407b through the
contact hole 408a.
The pixel electrode 409 is formed of a transparent conductive film
or a metal thin film containing aluminium. A conductive film (a
transparent conductive film or a metal thin film) is formed on the
planarization film 408 by a sputtering method. Then, the conductive
film is patterned by the photolithography method. The pixel
electrode 409 is thereby formed on the planarization film 408. In
the case of a driving TFT of an organic EL display, the organic EL
light emitting device 312a, the color filter (CF) 313a, and the
like as shown FIG. 16 are formed on the pixel electrode 409. Note
that, in the case of a top-emission type organic EL display, the
pixel electrode 409 is formed of a metal thin film containing
aluminium or silver which have a high reflectance. In the case of a
bottom-emission type organic EL display, the pixel electrode 409 is
formed of a transparent conductive film such as ITO.
The processes for manufacturing an inverted staggered TFT has been
described. The manufacturing method according to the present
embodiment may be applied to manufacture of an inverted staggered
TFT. It is obvious that the manufacturing method of a TFT is not
limited to a TFT for an organic EL display and can be applied to
manufacture of a TFT for a liquid crystal display (LCD).
In addition, it has been described that the laser annealing
apparatus according to the present embodiment irradiates an
amorphous silicon film with a laser beam to form a polysilicon film
in the above description, but the laser annealing apparatus may
irradiate an amorphous silicon film with a laser beam to form a
micro-crystal silicon film. Furthermore, a laser beam for
performing annealing is not limited to excimer laser. In addition,
the method according to the present embodiment can be applied to a
laser annealing apparatus that crystallizes thin films other than a
silicon film. That is, as long as the laser annealing apparatus
irradiates an amorphous film with a laser beam to form a
crystallized film, the method according to the present embodiment
can be applied. It is possible for the laser annealing apparatus
according to the present embodiment to properly evaluate a
substrate with a crystallized film.
In the above description, it has been described that the
manufacturing method according to the present embodiment is applied
to manufacture of a TFT array substrate for a display device, such
as an organic EL display or a crystal display. However, the method
can be applied to manufacture of a TFT array substrate for other
display devices. Furthermore, the manufacturing method according to
the present embodiment can be used for other TFT array substrates
except for a display device. For example, the semiconductor device
according to the present embodiment may be used for a TFT array
substrate for a flat panel detector such as an X-ray image sensor.
It is possible to manufacture a TFT array substrate having a
uniform semiconductor layer characteristic with high
productivity.
(Determination Method of Optimized Energy Density)
With reference to FIGS. 25 and 26, a method for determining an
optimized energy density (OED) of the laser beam L1 with which a
substrate is to be irradiated is described. FIG. 25 is a flowchart
showing a method for determining the OED. FIG. 26 is a schematic
diagram for explaining regions of a substrate in the method for
determining the OED.
Here, the substrate 100 is divided into a plurality of regions in
the X direction. As shown in FIG. 26, the divided regions are
referred to as a region Xn-1, a region Xn, a region Xn+1, a region
Xn+2, and the like. Note that, the substrate 100 is irradiated with
the laser beam L1 and the probe beam L2 in the order of the region
Xn-1, the region Xn, the region Xn+1, and the region Xn+2. Thus,
after the transmittance at the region Xn-1 is measured, the
transmittance at the region Xn is measured.
At the region Xn-1, the region Xn, the region Xn+1, and the region
Xn+2, the measured transmittances are respectively referred to as a
transmittance Tn-1, a transmittance Tn, a transmittance Tn+1, and a
transmittance Tn+2. At each region, a plurality of detection values
of the transmittance is acquired. For example, the transmittance Tn
contains a plurality of detection values. Then, the standard
deviation of the detection values of the transmittance Tn-1 is
referred to as a standard deviation .sigma.n-1. The standard
deviations of the detection values of the transmittance Tn, the
transmittance Tn+1, and the transmittance Tn+2 are respectively
referred to as a standard deviation .sigma.n, a standard deviation
.sigma.n+1, and a standard deviation .sigma.n+2.
First, the processing apparatus 26 calculates the standard
deviation .sigma.n-1 at the region Xn-1 (S21). Then, the processing
apparatus 26 compares the standard deviation .sigma.n-1 with a
threshold .sigma.th of the standard deviation (S22). When the
standard deviation .sigma.n-1 is greater than the threshold
.sigma.th, the irradiation intensity of the laser beam L1 (energy
density) is changed (S23). That is, a laser beam source 11
increases or lowers the output. When the standard deviation
.sigma.n-1 is equal to or less than the threshold .sigma.th, the
irradiation intensity of the laser beam L1 is maintained (S24).
Next, the processing apparatus 26 calculates the standard deviation
.sigma.n at the region Xn (S25). Then, the processing apparatus 26
compares the standard deviation .sigma.n with the threshold
.sigma.th of the standard deviation (S26). When the standard
deviation .sigma.n is greater than the threshold .sigma.th, the
irradiation intensity of the laser beam L1 is changed (S27). That
is, the laser beam source 11 increases or lowers the output. The
output of a probe beam source 21 is determined to be increased or
lowered in S27 based on the comparison result of the standard
deviation .sigma.n with the standard deviation .sigma.n-1t. Then,
the calculation n=n+1 is performed, that is, n is incremented, and
the processing from S21 is consecutively performed. When the
standard deviation .sigma.n is equal to or less than the threshold
.sigma.th, the irradiation intensity of the laser beam L1 is
maintained (S28).
It is thereby possible to determine the OED of the laser beam L1.
In addition, while the substrate 100 is being irradiated with the
laser beam L1, the photodetector 25 detects the probe beam L3.
Thus, it is possible to optimize the energy density of the laser
beam L1 in real time. That is, when the standard deviation of the
transmittance is greater than the threshold .sigma.th, the laser
beam source 11 changes the irradiation intensity of the laser beam
L1. Accordingly, it is possible to reduce the standard deviation of
the transmittance at the next region. Thus, it is possible to form
a high-quality polysilicon film.
Third Embodiment
An ELA apparatus 500 according to a third embodiment is described
with reference to FIGS. 27 and 28. FIG. 27 is a side view
schematically showing a configuration of the ELA apparatus 500, and
FIG. 28 is a plan view. As shown in FIG. 27, the ELA apparatus 500
includes a mirror 512, a projection lens 513, a probe beam source
521, a lens 523, a condenser lens 524, a photodetector 525, a door
valve 543, a chamber 550, a surface plate 556, a drive mechanism
557, a suction stage 558, and a pusher pin 559.
In the present embodiment, the arrangement of the optical system
for a probe beam, specifically, the arrangement of the probe beam
source 521 and the photodetector 525 is different from that in the
first and second embodiments. When a conveying robot 504 carries a
substrate 100 out of the ELA apparatus 500, an inspection with a
probe beam is performed. That is, after annealing treatment with a
laser beam L1 is finished, an inspection with a probe beam L2 is
performed. In addition, the suction stage 558 instead of the
gas-floating unit 43 described in the second embodiment holds the
substrate 100 in the present embodiment. The configuration and
processing except for these points are similar to the ELA apparatus
500 in the first and second embodiments, and the description is
omitted. For example, the optical system for irradiating the
substrate 100 with the laser beam L1 is similar to that in the
first embodiment. In addition, the inspection method with a probe
beam is also similar to that in the first and second embodiments,
and the description is omitted.
The ELA apparatus 500 includes a treatment chamber 550 surrounding
a treatment room 541. The inside of the treatment chamber 550 is
the treatment room 541. The treatment room 541 is in inert gas
atmosphere, for example, nitrogen gas or the like. A carrying-out
port 541b is provided at a side wall 551 of the treatment chamber
550. The carrying-out port 541b is provided at the end portion of
the treatment chamber 550 at the +X side. Then, the conveying robot
504 is disposed outside the treatment chamber 550. The conveying
robot 504 includes a robot hand 505 capable of entering the
treatment room 541 through the carrying-out port 541b.
The conveying robot 504 carries the substrate 100 at a carrying-out
position out through the carrying-out port 541b. That is, the robot
hand 505 enters the treatment room 541 from the carrying-out port
541b and takes out the substrate 100 subjected to the treatment
from the treatment room 541. As shown in FIG. 28, the robot hand
505 moves the substrate 100 in the +X direction, and the substrate
100 is carried out of the treatment room 541 through the
carrying-out port 541b. The conveying robot 504 carries the
carried-out substrate 100 in a cassette.
Note that, the carrying-out port 541b may be used as a carrying-in
port. That is, the conveying robot 504 may carry the substrate 100
before the treatment through the carrying-out port 541b.
Alternatively, a carrying-in port separately from the carrying-out
port 541b may be provided to the treatment chamber 550. The
carrying-out port 541b is provided with the door valve 543. The
door valve 543 is opened at the time of carrying the substrate 100
out or the like, and the door valve 543 is closed at the time of
the irradiation with the laser beam L1.
The surface plate 556, the drive mechanism 557, and the suction
stage 558 are provided in the treatment room 541. The surface plate
556 is fixed in the treatment chamber 550. The suction stage 558 is
attached to the surface plate 556 through the drive mechanism 557.
As shown in FIG. 28, the drive mechanism 557 includes an X shaft
557X that moves the suction stage 558 in the X direction and a
shaft 557Y that moves the suction stage 558 in the Y direction. As
described in the first embodiment, the laser beam L1 is a line beam
having its longitudinal direction in the Y direction on the
substrate 100. The drive mechanism 557 moves the suction stage 558
in the X direction. Accordingly, while the suction stage 558 is
moving the substrate 100 along a conveying path, the substrate 100
is irradiated with the laser beam L1. In addition, the drive
mechanism 557 may have a .theta. shaft that rotates the suction
stage 558 about the Z axis.
The suction stage 558 sucks and holds the substrate 100. The
suction stage 558 is provided with the pusher pin 559 for carrying
the substrate 100 in and out. The pusher pin 559 is provided so as
to be raised and lowered. When the substrate 100 is carried in or
out, the pusher pin 559 is raised to transfer the substrate 100 to
the robot hand 505.
Specifically, when the pusher pin 559 is raised while the substrate
100 is on the suction stage 558, a gap is generated between the
substrate 100 and the suction stage 558. Then, the robot hand 505
enter the gap between the substrate 100 and the suction stage 558.
When the pusher pin 559 is lowered while the robot hand 505 is
being under the substrate 100, the robot hand 505 holds the
substrate 100.
Alternatively, the robot hand 505 conveys the substrate 100 onto
the suction stage 558 while the pusher pin 559 is being lowered.
Then, when the pusher pin 559 is raised, the pusher pin 559 holds
the substrate 100. When the pusher pin 559 is lowered while the
substrate 100 is being placed on the pusher pin 559, the substrate
100 is placed onto the suction stage 558. Accordingly, the suction
stage 558 becomes ready to suck the substrate 100. The suction
stage 558 sucks the substrate 100 at the time of the irradiation
with the laser beam L1. When the irradiation with the laser beam L1
is finished, the suction stage 558 releases the suction.
The probe beam source 521, the lens 523, the condenser lens 524,
and the photodetector 525 are further provided in the treatment
room 541. The probe beam source 521, the lens 523, the condenser
lens 524, and the photodetector 525 are disposed in the vicinity of
the side wall 551. For example, the probe beam source 521, the lens
523, the condenser lens 524, and the photodetector 525 are fixed on
the surface at the treatment room 541 side of the side wall 551.
For example, while the suction stage 558 is being stopped at the
substrate carrying-out position (the endmost of the +X side), the
probe beam source 521 emits the probe beam L2.
The probe beam L2 emitted from a probe beam source L2 is condensed
by the lens 523 and enters the substrate 100. During the robot hand
505 conveys the substrate 100, a polysilicon film 101b is
irradiated with the probe beam L2 outside the suction stage 558. A
probe beam L3 transmitted through the substrate 100 is condensed by
the condenser lens 524 on the photodetector 525. The photodetector
525 outputs detection signals to a processing apparatus (the
illustration is omitted) as described above.
When the robot hand 505 carries the substrate 100 out through the
carrying-out port 541b to the outside of the treatment room 541, an
inspection with the probe beam L2 can be performed. The robot hand
505 carries the substrate 100 on the suction stage 558 out, and the
irradiation position of the probe beam L2 is changed toward the +X
direction. During the robot hand 505 carries the substrate 100 out,
the substrate 100 passes between the lens 523 and the condenser
lens 524. The probe beam L2 from the probe beam source 521 is
condensed by the lens 523 on the substrate 100. The probe beam L2
forms an illumination region P2 outside the suction stage 558 (see
FIG. 28). Note that, the illumination region P2 of the probe beam
L2 has a linear shape extending in the Y direction, but may have a
point-like shape.
The probe beam L3 having passed through the polysilicon film 101b
of the substrate 100 is condensed by the condenser lens 524 on the
photodetector 525. During the robot hand 505 carries the substrate
100 out, the photodetector 525 detects the probe beam L3. That is,
the robot hand 505 moves the substrate 100 in the +X direction in
order for the robot hand 505 to carry the substrate 100 out through
the carrying-out port 541b. While the substrate 100 is being moved
in the +X direction, the photodetector 525 detects the probe beam
L3. It is thereby possible to measure the transmittance of the
polysilicon film 101b of the substrate 100 in an inspection line IL
as shown in FIG. 28. Note that, since the robot hand 505 moves the
substrate 100 in the +X direction, the inspection line IL has a
belt-like shape or a line shape having its longitudinal direction
in the X direction.
The annealing laser beam L1 forms a linear irradiation region P1
having its longitudinal direction in the Y direction (see FIG. 3).
On the other hand, the robot hand 505 moves the substrate 100 in
the X direction. Thus, at the time of the inspection with a probe
beam, the substrate 100 is scanned along the latitudinal direction
of the irradiation region P1. It is thereby possible to properly
evaluate shot unevenness.
Unlike the gas-floating unit, it can be difficult for the suction
stage 558 to be provided with the optical path of a probe beam.
Although this suction stage 558 is used, it is possible for the
photodetector 525 to detect the probe beam L3 transmitted through
the substrate 100 with the configuration in the present embodiment.
Thus, it is possible to properly inspect the substrate 100. When
the substrate 100 is determined to be abnormal based on the
standard deviation or the average value of the detection values,
the substrate 100 is carried in the ELA apparatus 500 and
re-irradiated with the laser beam L1. For example, the portion
having shot unevenness or the entire substrate 100 may be
re-irradiated with the laser beam L1. Accordingly, it is possible
to improve the yield.
The lens 523 forms the illumination region P2 of the probe beam L2
at the X position between the carrying-out port 541b and the
suction stage 558. In the substrate conveying process by the robot
hand 505, the substrate 100 is moved for a longer distance than the
substrate 100. In the X direction in which the substrate 100 is
conveyed, the inspection line IL is formed over the entire
substrate 100. By evaluating the transmittance in the inspection
line IL, it is possible to evaluate the crystalline state of the
polysilicon film 101b. In addition, since the inspection can be
performed in the substrate conveying process, it is unnecessary to
convey the substrate 100 only for performing the inspection.
Accordingly, it is possible to prevent the increase in tact time.
Furthermore, the probe beam source 521, the lens 523, the condenser
lens 524, and the photodetector 525 are attached in the vicinity of
the side wall 551. Thus, it is possible to prevent a space for
providing an optical system from increasing.
In addition, two illumination regions P2 of the probe beam L2 are
formed on the substrate 100 as shown in FIG. 28 in the present
embodiment. That is, the substrate 100 is irradiated simultaneously
with the two probe beams L2 separated in the Y direction.
Accordingly, it is possible to simultaneously measure the
transmittances of the two portions of the substrate 100. It is
thereby possible to more reliably perform evaluation.
For example, when particles are attached to a substrate, abnormal
values indicating that the transmittance is greatly lowered can be
detected at the points of particles. When such abnormal values are
detected, the standard deviation of the detection values is greatly
affected. However, it is difficult to determine whether the
abnormal values are caused by particles or by the crystalline
state. Thus, by irradiating the substrate with the two or more
separated probe beams L2 as described in the present embodiment, it
is possible to eliminate the influence of the abnormal values
caused by particles. That is, when one abnormal value at the same X
position is detected, the abnormal value is determined to be caused
by particles, or when abnormal values are detected at two portions,
the abnormal values are determined to be caused by shot unevenness.
Thus, by eliminating abnormal values caused by particles to
calculate the standard deviation, it is possible to more reliably
perform evaluation.
Note that, it has been described that the robot hand 505 conveys
the substrate 100 along the latitudinal direction of the
irradiation region P1 of the laser beam L1 in the above
description, but the latitudinal direction of the irradiation
region P1 of the laser beam L1 may not be the same as the conveying
direction of the robot hand 505. For example, before the
irradiation with the laser beam L1, the suction stage 558 can
rotate the substrate 100 about the Z axis (in the .theta.
direction) by 90.degree.. Alternatively, the robot hand 505 can
move the substrate 100 in the Y direction according to the position
of a carrying-out port 541. In such cases, the latitudinal
direction of the irradiation region P1 of the laser beam L1 is
orthogonal to the conveying direction of the robot hand 505. That
is, the inspection line IL is parallel to the longitudinal
direction of the irradiation region P1 of the laser beam L1.
In this case, scanning unevenness instead of shot unevenness of the
laser beam L1 can be evaluated. Note that, scanning unevenness is
not caused by laser but by an optical system and also referred to
as optics unevenness. Specifically, if particles or the like are
attached to the optical element included in the optical system of
the laser beam L1, a shadow appears on a part of the irradiation
region P1. Since the detection light amount is lowered at the
position where the shadow appears, an abnormal value is detected.
The shadow appears at the same position in the irradiation region
P1, abnormal values are detected along the line parallel to the
latitudinal direction of the irradiation region P1. Thus, abnormal
values occur in the line at the same position regardless of the
substrate 100, which indicates that there is scanning unevenness.
Note that, in order to both evaluate scanning unevenness and shot
unevenness, it is only required to evaluate a substrate irradiated
with a laser at the suction stage set to 0.degree. and the
substrate irradiated with a laser at the suction stage rotated by
90.degree..
Note that, when the robot hand 505 carries the substrate 100 out,
the substrate 100 can be bent and moved up and down. When the
substrate 100 is moved up and down, the size of the illumination
region P2 on the substrate 100 is changed. That is, the
illumination region P2 has the smallest size when the focal point
of the probe beam L2 by the lens 523 is on the substrate 100, but
the size of the illumination region P2 becomes larger as the
substrate 100 is separated farther from the focal point.
FIG. 29 shows the size of the probe beam L2 at the Z position when
the focal point at the Z position is set as 0. FIG. 29 shows a
simulation result when the probe beam L2 having the wavelength of
405 nm and the size of 4 mm is condensed by the lens 523 of 300 mm.
The horizontal axis indicates a Z position, and the vertical axis
indicates the size of the probe beam L2. In FIG. 29, the size of
the probe beam L2 is about 38 .mu.m at the focal point. When the Z
position is shifted by .+-.2 mm, the size of the probe beam L2 is
47 .mu.m, and this does not matter practically. That is, if the
probe beam L2 having the size of 47 .mu.m passes though the
substrate 100, the photodetector 525 detects the probe beam L3
transmitted through the substrate 100 by the condenser lens
524.
(Optical System for Probe Beam)
Next, a configuration of an optical system for a probe beam in an
ELA apparatus according to a third embodiment is described. FIGS.
30 to 32 are diagrams showing configurations of optical systems for
the probe beam L2. FIGS. 30 to 32 each show an optical system that
irradiates the substrate 100 with the probe beam L2 and detects the
probe beam L3 transmitted through the substrate 100.
<Optical System 501>
FIG. 30 is a schematic diagram showing an example of an optical
system (referred to as an optical system 501). The optical system
501 includes a probe beam source 521, a one-side expander 526, a
lens 523, a mirror 522, a mirror 529, a collimation lens 528, a
condenser lens 524, and a photodetector 525.
The probe beam source 521 generates a probe beam L2 having a
wavelength of 405 nm. The probe beam L2 from the probe beam source
521 enters the one-side expander 526. The one-side expander 526 has
two lenses and expands the beam diameter in the Y direction. Note
that, the conveying direction of the substrate 100 by the robot
hand 505 is the X direction. The substrate 100 is irradiated with
the probe beam L2 from the one-side expander 526 through the lens
523 and the mirror 522. Note that, the lens 523 is a cylindrical
lens and condenses the probe beam L2 in the X direction. Thus, the
probe beam L2 forms, on the substrate 100, a linear illumination
region having its longitudinal direction in the Y direction and its
latitudinal direction in the X direction.
The probe beam L3 transmitted through the substrate 100 is
reflected by the mirror 529 and enters the collimation lens 528.
The collimation lens 528 turns the probe beam L3 into a parallel
luminous flux. The probe beam L3 having passed through the
collimation lens 528 enters the condenser lens 524. The condenser
lens 524 condenses the probe beam L3 on the light-receiving surface
of the photodetector 525. The photodetector 525 is provided with a
band-pass filter 525a. The band-pass filter 525a transmits light
having a wavelength of 405 nm. Accordingly, it is possible to
prevent stray light having a wavelength other than the wavelength
of the probe beam from entering the photodetector 525.
With the optical system 501, it is possible to properly evaluate
the crystalline state. In addition, the optical system 501 may be
provided with a camera 530 that confirms the focal point of the
lens 523. A camera 30 captures an image of the illumination region
of the probe beam L2 and its surroundings. The focal point can be
adjusted based on the image by the camera 530. The camera 530 may
be provided only at the time of installing the optical system
501.
<Optical System 502>
FIG. 31 is a schematic diagram showing another example of an
optical system for a probe beam (referred to as an optical system
502). The optical system 502 has a configuration for detecting a
probe beam having passed through the substrate 100 twice. The
optical system 502 includes a probe beam source 521, a one-side
expander 526, a lens 523, a mirror 522, a mirror 531, a collimation
lens 532, a condenser lens 533, a mirror 534, a mirror 529, a
collimation lens 528, a condenser lens 524, and a photodetector
525.
The probe beam source 521 generates a probe beam L2 having a
wavelength of 405 nm. The probe beam L2 from the probe beam source
521 enters the one-side expander 526. The one-side expander 526 has
two lenses and expands the beam diameter in the Y direction. The
substrate 100 is irradiated with the probe beam L2 from the
one-side expander 526 through the lens 523 and the mirror 522. Note
that, the lens 523 is a cylindrical lens and condenses the probe
beam L2 in the X direction. Thus, the probe beam L2 reflected by
the mirror 522 forms, on the substrate 100, a linear illumination
region having its longitudinal direction in the Y direction and its
latitudinal direction in the X direction.
The probe beam L2 transmitted through the substrate 100 is
reflected by the mirror 531 and enters the collimation lens 532.
The collimation lens 532 turns the probe beam L2 into a parallel
luminous flux. The probe beam L2 from the collimation lens 532
enters the substrate 100 through the condenser lens 533 and the
mirror 534. Note that, the condenser lens 533 is a cylindrical lens
and condenses the probe beam L2 in the X direction. Thus, the probe
beam L2 reflected by the mirror 534 forms, on the substrate 100, a
linear illumination region having its longitudinal direction in the
Y direction and its latitudinal direction in the X direction.
The probe beam L3 transmitted through the substrate 100 is
reflected by the mirror 529 and enters the collimation lens 528.
The collimation lens 528 turns the probe beam L3 into a parallel
luminous flux. The probe beam L3 having passed through the
collimation lens 528 enters the condenser lens 524. The condenser
lens 524 condenses the probe beam L3 on the light-receiving surface
of the photodetector 525. The photodetector 525 is provided with a
band-pass filter 525a. The band-pass filter 525a transmits light
having a wavelength of 405 nm. Accordingly, it is possible to stray
light having a wavelength other than the wavelength of the probe
beam from entering the photodetector 525.
In this manner, the photodetector 525 detects the probe beam L3
having passed through the polysilicon film 101b twice in the
optical system 502. Accordingly, it is possible to emphasize
transmittance unevenness. Thus, it is possible to properly evaluate
the crystalline state.
The focal point by the lens 523 is shifted from the focal point by
the condenser lens 533 in the Y direction on the substrate 100.
That is, when the conveying direction by the robot hand 505 is the
X direction, the probe beam L2 has passed through the substrate 100
twice at different Y positions and at the same X position.
Accordingly, since shot unevenness is emphasized, it is possible to
properly evaluate the crystalline state. Naturally, the optical
system 502 may be configured so that a probe beam passes through
the polysilicon film 101b three times or more. For example, a
mirror and a lens can be added in order for a probe beam to pass
through the polysilicon film 101b three times or more.
The first and second positions where the probe beam L2 passes
through the substrate 100 are separated in the Y direction. Thus,
it is possible to reduce the influence of particles. For example,
if a particle is attached to the first passing position, the
particle is not attached to the second passing position. Thus, it
is possible to reduce the influence of particles on lowering the
transmittance. Accordingly, it is possible to properly evaluate the
crystalline state.
The optical system 502 may be provided with cameras 530a and 530b
that respectively confirm the focal points of the lens 523 and the
condenser lens 533. The cameras 530a and 530b each capture an image
of the illumination region of the probe beam L2 and its
surroundings. The focal points can be adjusted based on the images
by the cameras 530a and 530b. The cameras 530a and 530b may be
provided only at the time of installing the optical system 502.
<Optical System 503>
FIG. 32 is a schematic diagram showing another example of an
optical system for a probe beam (referred to as an optical system
503). The optical system 503 has a configuration for detecting a
probe beam having passed through the substrate 100 twice. In
addition, the probe beam L2 passes through the substrate 100 at the
same position twice in an optical system 303. The optical system
503 includes a probe beam source 521, a one-side expander 526, a
polarizing plate 536, a lens 523, a beam splitter 537, a condenser
lens 533, a quarter-wavelength plate 538, a mirror 539, a
collimation lens 528, a condenser lens 524, and a photodetector
525.
The probe beam source 521 generates a probe beam L2 having a
wavelength of 405 nm. The probe beam L2 from the probe beam source
521 enters the one-side expander 526. The one-side expander 526
expands the beam diameter in the Y direction. The substrate 100 is
irradiated with the probe beam L2 from the one-side expander 526
through the polarizing plate 536, the lens 523, and the beam
splitter 537. The polarizing plate 536 turns the probe beam L2 into
linearly polarized light along a first direction. The beam splitter
537 is, for example, a polarizing beam splitter, reflects the
linearly polarized light along the first direction, and transmits
linearly polarized light along a second direction orthogonal to the
first direction. Thus, the beam splitter 537 reflects the probe
beam L2 toward the substrate 100.
The lens 523 is a cylindrical lens and condenses the probe beam L2
in the X direction. Accordingly, the probe beam L2 forms, on the
substrate 100, a linear illumination region having its longitudinal
direction in the Y direction and its latitudinal direction in the X
direction.
The probe beam L2 transmitted through the substrate 100 enters the
condenser lens 533 which is a cylindrical lens. The condenser lens
533 functions as a collimation lens that turns the probe beam L2
from the substrate 100 into a parallel luminous flux. The probe
beam L2 from the condenser lens 533 is reflected by the mirror 539
through the quarter-wavelength plate 538. The mirror 539 is a total
reflection mirror and makes the probe beam L2 transmitted through
the quarter-wavelength plate 538 enter the quarter-wavelength plate
538 again. Since the probe beam L2 passed through the
quarter-wavelength plate 538 twice, the linearly polarized light is
rotated by 90.degree.. Thus, the probe beam L2 directed from the
quarter-wavelength plate 538 toward the substrate 100 is linearly
polarized light along the second direction.
The probe beam L2 having passed through the quarter-wavelength
plate 538 twice is condensed by the condenser lens 533 on the
substrate 100. As described above, the probe beam L2 forms, on the
substrate 100, a linear illumination region having its longitudinal
direction in the Y direction and its latitudinal direction in the X
direction. The probe beam L3 transmitted through the substrate 100
enters the beam splitter 537. As described above, the probe beam L3
is linearly polarized light along the second direction and
transmitted through the beam splitter 537. The probe beam L3
transmitted through the beam splitter 537 enters the collimation
lens 528.
The collimation lens 528 turns the probe beam L3 into a parallel
luminous flux. The probe beam L3 having passed through the
collimation lens 528 enters the condenser lens 524. The condenser
lens 524 condenses the probe beam L3 on the light-receiving surface
of the photodetector 525. The photodetector 525 is provided with a
band-pass filter 525a. The band-pass filter 525a transmits light
having a wavelength of 405 nm. Accordingly, it is possible to stray
light having a wavelength other than the wavelength of the probe
beam from entering the photodetector 525.
In this manner, the photodetector 525 detects the probe beam L3
having passed through the polysilicon film 101b twice in the
optical system 503. Accordingly, it is possible to emphasize
transmittance unevenness. In addition, the focal point by the lens
523 and the focal point by the condenser lens 533 are at the same
position on the substrate 100. Accordingly, it is possible to
emphasize shot unevenness and to more properly evaluate the
crystalline state.
Note that, the probe beam L2 has passed through the substrate 100
at the same position in the optical system 503. The optical system
503 may be provided with a camera 530 that confirms the focal
points of the lens 523 and the condenser lens 533. The camera 530
captures an image of the illumination region of the probe beam L2
and its surroundings. The focal points can be adjusted based on the
image by the camera 530. The camera 530 may be provided only at the
time of installing the optical system 503.
FIG. 33 is a graph showing the average value and the standard
deviation of the detection signals acquired by the photodetector
52. FIG. 33 shows a measurement result when the energy density is
changed in the range from 400 to 435 mJ/cm.sup.2 and at a pitch of
5 mJ/cm.sup.2. When the energy density is 420 mJ/cm.sup.2 and 425
mJ/cm.sup.2, the average values of the detection signals are low.
Thus, the OED is to be either 420 mJ/cm.sup.2 or 425
mJ/cm.sup.2.
However, the average values at 420 mJ/cm.sup.2 and 425 mJ/cm.sup.2
are nearly the same, and it is difficult to obtain the OED from the
average values. On the other hand, the standard deviation at 420
mJ/cm.sup.2 is less than the standard deviation at 425 mJ/cm.sup.2.
Thus, the OED can be set to 420 mJ/cm.sup.2. In this manner, by
using the average values and the standard deviations of the
detection values, it is possible to properly determine the OED.
The present invention is not limited to the above-described
embodiments, various modifications can be made without departing
from the spirit and scope of the present invention.
This application is based upon and claims the benefit of priority
from Japanese patent application No. 2016-163693, filed on Aug. 24,
2016 and Japanese patent application No. 2017-112516, filed on Jun.
7, 2017, the disclosure of which is incorporated herein in its
entirety by reference.
REFERENCE SIGNS LIST
1 Laser annealing apparatus 11 Laser beam source 12 Mirror 13
Projection lens 21 Probe beam source 22 Mirror 23 Lens 24 Condenser
lens 25 Photodetector 26 Treatment apparatus 100 Substrate 101
Silicon film 300 Organic EL display 310 Substrate 311 TFT layer
311a TFT 312 Organic layer 312a Organic EL light emitting device
312b Partition wall 313 Color filter layer 313a Color filter (CF)
314 Sealing substrate 401 Glass substrate 402 Gate electrode 403
Gate insulating film 404 Amorphous silicon film 405 Polysilicon
film 406 Interlayer insulating film 407a Source electrode 407b
Drain electrode 408 Planarization film 409 Pixel electrode 410 TFT
PX Pixel
* * * * *